Crocodile

CROCODILE, in a restricted sense, any reptile of the genus Crocodilus, of which 12 living species occur in warm regions of the world, or of two allied African genera, Osteolaemus and Osteoblepharon, having a single species each; members of these 14 species are true crocodiles as distinguished from the alligators. Broadly, however, the term crocodile is used to denote any member of the order Crocodilia, or Loricata, which includes, in addition to the 14 species of true crocodiles, two gavials, one each in India and Malaysia; two alligators, one each in China and in the United States; and seven caymans, all found in Central and South America. The true crocodiles, having sharply tapering heads, expose the fourth tooth on either side of the lower jaw in a notch on the outside of the upper jaw. The broad-headed alligators and caymans have the fourth tooth concealed in a matching socket in the overhanging upper jaw. The alligator is distinguished from the gavial and crocodile by the teeth of the upper jaw, which overlap those of the lower jaw markedly. The gavials are fish feeders exclusively and are easily distinguished from others by their long narrow snouts, which offer little resistance to the water when swung sidewise to catch fish. The caymans of Central and South America are much like the alligators, but they lack a bony septum in the nose. Crocodilians are survivors of a group that flourished with the dinosaurs and once included specimens over 50 feet (15 meters) long. Its earliest members date from the lower Jurassic. They appear, from the fossil record, to have been most numerous in Europe and North America until quite recent times. In the Pleistocene, crocodilians have been found in India and Africa, as well as in Europe and North America. Crocodilians are among the largest living reptiles, but specimens are seldom as large as those described in print. The American crocodile, C. acutus; the Orinoco crocodile, C. intermedius; and the marine crocodile, C. porosus, found in the Australo-Malay Archipelago, all reach about 23 feet (7 meters). The last named is reported to reach lengths of more than 30 feet (9 meters), but such reports are probably exaggerations or miscalculations. The Cuban crocodile, C. rhombifer, a rare species found only in Cuba, reaches a length of 12 feet (3.6 meters). The smallest crocodilians are the Chinese alligator, Alligator sinensis, which attains a length of about 5 feet (1.5 meters), and one of the South American caymans, Caiman palpebrosus, which seldom reaches a length of 4 feet (120 cm). Most crocodilians live most of the time in the water, where they frequently float lazily with only the nostrils, eyes, and ears, which are raised above the general level of the head, projecting above the surface. At such times a fleshy valve in the rear of the mouth prevents water from entering the air passages, and an internal passage in the skull conducts air from the projecting nostrils to the throat. The powerful, vertically flattened tail and webbed feet facilitate swimming, but only the marine crocodile ventures far from land. Crocodilians come ashore to build their nests and to lay their eggs, and sometimes to bask in the sun, lying agape to dry out the leeches that infest their mouths; when disturbed they run into the water with a speed that is surprising in view of the tremendous girth of large specimens. The eggs, laid in a pile of decaying vegetation or in holes in the sand, are ellipsoidal in shape, and their shells are leathery. The young, on hatching, grow rapidly. In captivity the young of the American alligator are about 18 inches (45 cm) long at the end of the first year, and at about the third year they are roughly 3 feet (90 cm) long. The age of crocodilians has always been exaggerated; the animals look old at birth, and this fact has led to much fanciful speculation. Large specimens of any species may be assumed to be in their thirties; exceptionally large individuals, in their forties. Zoo specimens have lived 25 years, and one American alligator survived 56 years. Any large crocodilian, either on shore or in the water, may prove dangerous to man. This reptile does not attack indiscriminately, but it is fast. Its tail is flexible and powerful, and on land it can run well in a straight line. Its characteristic attack is a slow, careless approach terminating in a sudden rush. When its jaws are set in a large animal it rotates or spins on its long axis, thus tearing its mouthful of flesh out of the larger body. It sinks large animals in the water, eating the flesh when it begins to decompose. In nature, full grown specimens have no enemies but man. The young, however, are preyed upon by many large birds, mammals, and fishes. Economically, crocodilians are definitely valuable, particularly for their hides, which have been widely used for shoes, bags, belts, and other purposes. This value has led to their extermination in many areas, with the result that most nations now protect their crocodiles. Furthermore, in some states of the United States, notably New York the sale of crocodilian products is forbidden. See also ALLIGATOR; CAIMAN, GAVIAL; REPTILES. ROBERT STUART MATHEWS